The term user equipment (UE for short) in this application means the (potentially moving) piece of equipment that communicates with the fixed network of radio transceivers called base stations in a mobile communications network. In different standards or circumstances it may be named differently, such as a terminal. The term user equipment used herein is, however, meant to encompass any such differently named equipment that serves the purpose mentioned above.
Likewise, nodeB or eNodeB (eNB for short) is a term often used within the Long Term Evolution (LTE) mobile communications network framework. However, the use of these terms in this application should not be interpreted to restrict the invention to the LTE framework. Rather, they should be interpreted in the broader sense as a radio basestation in any suitable mobile communications system.
In a wireless communication system it is well known that utilizing linear precoding at the transmitter side with multiple antennas can improve the performance substantially. FIG. 1 shows the block diagram related to downlink (DL) transmission with linear precoding in 3GPP LTE (Long Term Evolution) Rel-8/9/10 system.
Antenna ports shown in FIG. 1 convey the multiple transmitted signals that are spatially separable at the receiver. An antenna port is defined by its associated reference signal (RS). In practice, an antenna port may be implemented either as a single physical transmit antenna, or a combination of multiple physical antenna elements. Some proprietary operation might be implemented prior to mapping antenna port onto physical antenna elements. In either case, the signal transmitted from each antenna port is not designed to be further deconstructed by the receiver.
Layers are defined as strings or vectors of the modulated symbols to be transmitted on different antenna ports.